Americans' vitamin D levels are highest in August, lowest in February, study shows

June 21, 2013, University of California, Irvine

UC Irvine and Mayo Clinic researchers have found that vitamin D levels in the U.S. population peak in August and bottom out in February. The essential vitamin – necessary for healthy bones – is produced in the skin upon exposure to ultraviolet B rays from the sun.

helps bones absorb calcium and can protect against osteoporosis. It's also thought to play a role in seasonal illnesses, such as the flu. Low levels of vitamin D are believed to impair "innate immunity" i.e., the body's first line of defense against pathogens. To further study this link, good estimates of the cyclicality of the vitamin are necessary. Solar exposure – a timely topic since June 21 marks the first day of summer – is the most important way people acquire vitamin D. But certain foods, including egg yolks and oil-rich fish like mackerel, salmon, sardines and herring contain the nutrient. In addition, milk and cereal are often enriched with vitamin D.

"Even with food fortification, vitamin D levels in the population show a high level of seasonality due to the influence of sunlight," said Amy Kasahara, a UC Irvine graduate student in public health and first author on the paper, which appears in the journal PLOS ONE.

"The exact from to vitamin D were discovered in the 1970s," she said. "In this study, we have shown that vitamin D levels lag the , peaking in August and troughing in February."

The correlation between the seasons and vitamin D has been known for some time. "What we have been able to do is put a lot more precision on the estimates of vitamin D seasonality," said Andrew Noymer, associate professor of public health and senior author of the article.

"Our analysis, combined with other data, will help contribute to understanding the role of vitamin D in all seasonal diseases, where the simple winter/spring/summer/fall categories are not sufficient."

Researchers measured the level of 25-hydroxyvitamin D in 3.4 million blood samples collected weekly in the U.S. between July 2006 and December 2011.

The study looked at population averages, so people shouldn't make assumptions about their own levels of vitamin D based on the calendar. Healthcare providers can perform individual blood tests to measure vitamin D directly, and supplements are available for those who cannot or do not receive enough exposure to sunlight.

Ravinder J. Singh of the Mayo Clinic co-authored the work.

Explore further: Study reveals potential immune benefits of vitamin D supplements in healthy individuals

Related Stories

Study reveals potential immune benefits of vitamin D supplements in healthy individuals

March 20, 2013
Research from Boston University School of Medicine (BUSM) shows that improving vitamin D status by increasing its level in the blood could have a number of non-skeletal health benefits. The study, published online in PLOS ...

Low vitamin D levels a risk factor for pneumonia

April 30, 2013
A University of Eastern Finland study showed that low serum vitamin D levels are a risk factor for pneumonia. The risk of contracting pneumonia was more than 2.5 times greater in subjects with the lowest vitamin D levels ...

Study shows probiotic Lactobacillus reuteri NCIMB 30242 significantly increased vitamin D levels

June 19, 2013
A study published in the Journal of Clinical Endocrinology & Metabolism is the first report of an oral probiotic supplement significantly increasing circulating vitamin D levels in the blood.

Vitamin D benefits breathing in tuberculosis patients

March 26, 2013
Maintaining adequate levels of vitamin D can help people breathe better and may even protect against tuberculosis (TB), according to a recent study accepted for publication in The Endocrine Society's Journal of Clinical Endocrinology ...

Low levels of vitamin D are associated with mortality in older adults

October 2, 2012
Low levels of vitamin D and high levels of parathyroid hormone are associated with increased mortality in African American and Caucasian older adults, according to a new study accepted for publication in The Endocrine Society's ...

Excess vitamin E intake not a health concern, study says

April 15, 2013
Despite concerns that have been expressed about possible health risks from high intake of vitamin E, a new review concludes that biological mechanisms exist to routinely eliminate excess levels of the vitamin, and they make ...

Recommended for you

Self-lubricating latex could boost condom use: study

October 17, 2018
A perpetually unctuous, self-lubricating latex developed by a team of scientists in Boston could boost the use of condoms, they reported Wednesday in the journal Royal Society Open Science.

How healthy will we be in 2040?

October 17, 2018
A new scientific study of forecasts and alternative scenarios for life expectancy and major causes of death in 2040 shows all countries are likely to experience at least a slight increase in lifespans. In contrast, one scenario ...

Study finds evidence of intergenerational transmission of trauma among ex-POWs from the Civil War

October 16, 2018
A trio of researchers affiliated with the National Bureau of Economic Research has found evidence that suggests men who were traumatized while POWs during the U.S. Civil War transmitted that trauma to their offspring—many ...

Father's nicotine use can cause cognitive problems in children and grandchildren

October 16, 2018
A father's exposure to nicotine may cause cognitive deficits in his children and even grandchildren, according to a study in mice publishing on October 16 in the open-access journal PLOS Biology by Pradeep Bhide of Florida ...

Many supplements contain unapproved, dangerous ingredients: study

October 13, 2018
(HealthDay)—U.S. health officials have issued more than 700 warnings during the last decade about the sale of dietary supplements that contain unapproved and potentially dangerous drug ingredients, new research reveals.

Age at which women experience their first period is linked to their sons' age at puberty

October 12, 2018
The age at which young women experience their first menstrual bleeding is linked to the age at which their sons start puberty, according to the largest study to investigate this association in both sons and daughters.

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

neversaidit
1 / 5 (1) Jun 22, 2013
no SHIT.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.